1. Field of the Invention
The present invention relates to a medical biomaterial, particularly, to a capsular bag for artificial vitreous body, and a method for manufacturing the same.
2. Description of the Prior Art
Modern vitrectomy is a great revolution in ophthalmic therapy, thus allowing many ophthalmic disorders that would have previously been regarded as incurable to be cured. The operation indications thereof enlarge to several dozen kinds of ophthalmic disorders. It plays a great role in an ophthalmic clinic, and saves innumerable eyes that would go blind.
The normal vitreous body is a kind of gelatinous tissue that cannot regenerate. After vitrectomy, substitutes for vitreous body are required to fill the cavity of the removed vitreous body to support or plug the retina to prevent retinal detachment. Currently, national and international studies on substitutes for vitreous body are numerous, mainly including inert gas, silicone oil, heavy silicone oil, perfluorocarbon liquids, and hydrogels composed of high molecular weight hydrophilic polymers being the national or international research focus in the 1990s. Their therapy results, however, are not satisfying. Some of which could result in serious complications, for example, inert gas for instance C3F8 may easily cause a cataract, and lose the effect of tamponade at about two weeks after the surgery, such that it could not generate sustained top-pressure on the retina. Perfluorocarbon liquids are toxic to the retina, such that it would not settle in the cavity of vitreous body for a long time and could be utilized in surgery only. Additionally, perfluorocarbon liquids are easy to remain in the eyes and difficult to remove after reaction with water. Present substitutes for silicon oils widely used in clinics could result in glaucoma and cataract, and will self-emulsify within a particular time. The emulsified substitutes have to be removed. Upon removing, however, the retina can easily detach again. Repetitive surgeries not only aggravated the burden of patients, but also seriously impaired the vision of the patients. Even though the surgery is successful, the vision of the patients is very poor resulting from a low refractive index of silicon oil not generating adequate top pressure on the breaks underlying the retina, and that the diopter in the eyeball shifted to high hyperopia after tilling. Additionally, after surgeries, patients had to lie on their stomachs for a long time to prevent silicon oil from flowing into the anterior chamber, thus making the patients very agonized. Hydrogels mainly included PVP hydrogels, PVA hydrogels, PAM hydrogels, and Poly(1-vinyl-2-pyrrolidone) hydrogels, and so on. These hydrogels, however, are still at the experimental stage in opthalmology, and so far no one of these hydrogels has performed in clinic application, resulting in lack of observation on the long-term therapeutic effect on the toxicity to the eyes, and the price is very high. The patients could not afford it. Finding vitreous substitutes that met physiological needs and are more economical are required, which is one of the problems disturbing the doctors for vitreous retinal disorders in this century.
How to make an artificial vitreous body of which both structure and function are the same as those of the natural vitreous body is one of the keys to ensure the success of vitrectomy. Up to now, the components of the vitreous body have not been fully known. Based on the conditions of modern science and technology, the need to make an artificial vitreous body of which both structure and function are perfect is impractical. Therefore, without pursuing to make a fully physiological artificial vitreous body, the research thinking is changed to restore the most important function of the vitreous body, i.e., support of the retina so as to avoid repetitive retinal detachment, which is also a method to resolve the problem.
The current substitutes for a vitreous body are sometimes called an artificial vitreous body. Implantation methods are performed by directly injecting the substitutes for the vitreous body into the cavity of the vitreous body to support the retina to prevent the retina from detaching again. Chinese patent No. ZL 03126845.5 discloses a technical scheme about a capsular artificial vitreous body, which utilizes a system of an artificial vitreous body comprising a capsular bag made of high molecular weight film filled with water and having a drainage valve to achieve the object of supporting the retina and preventing the retina from detaching again. The capsular bag accommodates the shape and volume of the cavity of the human eyes. A drainage tube provided with a drainage valve is connected to the top of the capsular bag. The capsular bag and the drainage tube are hidden inside an assistant implanting means, i.e., an ejector handle. The head of the ejector handle can clamp the capsular bag. Since the capsular bag is manufactured manually with acetic acid and vinyl acetate copolymer, however, the technical scheme still has drawbacks, such as low biocompatibility and poor flexibility.